Gas-permeable elements for the flameless combustion of gaseous fuels have been used in portable and stationary heaters where transportable and substantially instantaneous sources of heat were required. Such elements have traditionally comprised ceramic fiber matrices containing appropriate metal catalysts. However, these elements have proven to be fragile and have tended to become cracked and their fibers broken off in use. Further, such elements have generally required careful control over the fuel-air mixture and flow rate minimize carbon monoxide production and to avoid either flashback of the combustion process into the gas supply chamber or blowout of the combustion reaction. Additionally, these combustion elements can only produce maximum heat outputs between 300 to 500 BTU/hr.in..sup.2 which require substantial pressure differentials across the element and are limited to maximum operating temperatures of up to approximately 2100 degrees F. in order to avoid melt-down of the elements themselves.
The best prior art known to Applicant representative of such burners are U.S., Pat. Nos. 3,322,179.; 3,367,149; 4,588,373; 4,067,956; 3,832,122; 4,280,329; and 4,252,520.